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Feedwater Limited
Tarran Way West
Tarran Estate
Moreton
WIRRAL
CH46 4TU
Telephone:
+44 151 606 0808
Fax:
+44 151 678 5459
Registered in
England & Wales
Number 1274270 |
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Case Study
Enviromate 5125 Helps Dairy to Stay within Consent Limits
Background
A food processing plant producing a variety of specialised dairy process products has problems with poor sludge settlement and a threat to their ammonia discharge levels. These are being caused by the huge variety of waste water arriving at the plant that includes large pH swings, glycol spills, very stringent use of cleaners/biocides and large variations in flow and organic load, both BOD and ammonia.
The above conditions presents a number of operational problems on the plant, one of which was poor settleability in the final clarifier resulting in the plant exceeding its consent levels for discharge to a water course
The causes for poor settleability can be numerous and are not always subject to one parameter, for which sludge age, high BOD/COD loading, variable F/M ratio, low dissolved oxygen and the presence of filamentous bacteria are but a few contributing factors. Furthermore, the overall effect can also exacerbate the problem as the return activated sludge (RAS) has a low concentration thus necessitating much longer pumping times to maintain the desired mixed liquor suspended solids (MLSS) in the aeration basin.
To help minimise the suspended solids carryover, it was also necessary to reduce the forward flow by as much as 80%, thus causing a backlog of wastewater waiting to be treated.
The system sludge loading rate – F/M – can vary between 0.05 and 0.7 kg’s BOD/kg MLSS/day and, as a consequence, sludge age can vary between 2.4 and 10 days. Current plant performance was well below expectations with high SVI of 250 compared with the optimal SVI of 100 – 150.
Goals
Minimise suspended solids carry over
Reduce SVI to between 100 – 150
Maintain the above with increasing flow.
Solution
Feedwater recommended evaluating their Enviromate range of products. Following jar etest studies. Feedwater proposed a chemical treatment programme using Enviromate 5125, a medium charge density cationic polymer. This was added to the flow from the aeration basin to the final clarifier at a rate of 5mg/L.
Enviromate 5125 is an easy to hand, easy to use polymer, eliminating the need for expensive polymer preparation units and day tanks.
Results
Application of the Enviromate 5125 aqueous dispersion product with its simple dosing set-up (see below) was easier than using conventional emulsion polymer technology.
At 5mg/l Enviromate 5125 produced a fast settling floc resulting in:
- Bringing the SVI to within desired parameters
- Minimising suspended solids carryover
- Restore the plant flow to operational levels
- Provide the potential to increase flow to reduce wastewater back-log.
Dosing system for Enviromate 5125
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